This invention relates to an automatically opening and closing closure device for use with containers of liquids or pastes, which device comprises an essentially rigid cap portion having a discharge orifice and a discharge duct leading thereto, beak means for pressing upon a flexible closing means when the closure device is in closed condition, and spring means for urging the beak means against the flexible closing means, but yielding to a determined excess pressure in the discharge duct to release the beak means and to let the flexible closing means expand to permit a discharge of liquid or paste from the discharge orifice as long as the excess pressure in the discharge duct prevails.
This invention also relates to collapsible tubes equipped with a closure device according to the invention which device opens automatically when manual pressure is applied to a flexible part of the wall of the collapsible tube away from the cap portion of the closure device. Such tubes can be filled with pasty materials such as any products of highly viscous pasty consistency, for instance, ointments, dentifrice, shaving creams, oil paints, mustard, liverwurst, mayonnaise, shoe polish, pasty shampoo, facial creams and the like. The closure device according to the invention can also be applied to tubes and similar containers filled with a liquid product, in which case the closure device must be designed to act with a higher closing force than in the case of tubes filled with a pasty material.
All hitherto known commercially available closure devices for tubes for dispensing pastes and the like contents require three manual operations for each single dispensing step. A first operation involves removal of the closure device, e.g. the unscrewing of a screwed-on internally threaded cap, a second operation whereby the tube wall remote from the cap is compressed to squeeze a cord or string of the pasty contents out of the mouth of the tube, and a third operation comprising placing the cap back on the tube to cover the mouth of the latter and to screw on the cap, or a similar closing operation. In particular, the third operation often makes contact of the fingers handling the closure means with residual pasty material about the mouth of the tube unavoidable. Moreover, screwing on the cap may squeeze material left in the threading on the socket of the tube containing the mouth out from under the cap and such residual material will be decomposed and soil the fingers of the user when opening the tube again.
Various attempts going back to the year 1925 have been made in the past to provide closure devices which do not require unscrewing and screwing-on of caps or the like manual contact with the discharge outlet of a collapsible tube. However, such closure devices have either been far too complicated and costly to be commercially acceptable, or they have failed to seal off the contents of the tube satisfactorily. Among closure devices proposed are those of U.S. Pat. Nos. 1,753,665 to Roos granted 1930, 1,881,488 granted in 1932 to Gleason, 2,682,974 granted 1954 to Smith and 2,755,974 granted in 1956 to Godfrey. British Pat. Nos. 240,091 and 1,007,657 and German Pat. Nos. 436,054 and 876,980 may also be mentioned, while closure devices requiring some handling of the discharge outlet of a collapsible tube fail to meet the requirements that manual contact with the vicinity of the tube mouth should be completely avoided. Among the latter are German Pat. No. 589,805, Swiss Pat. Nos. 232,797 and 368,744, and U.S. Pat. No. 3,684,137, as well as Belgian Pat. No. 508,572.